1. Field of the Invention
The present invention relates to an improvement in a snow removing machine comprising a body which includes a front portion with a snow removing section mounted thereto and a rear portion with an operating handle mounted thereto and having left and right grip portions to be gripped by an operator.
2. Description of the Related Art
In recent years, walking type snow removing machines having snow removing plates, which are propelled by means of crawler belts, have been widely used to reduce snow removing labor. One of such snow removing machines is arranged to enable snow removal work with the snow removing plate while adjusting the height of the snow removing plate by gripping grip portions of an operating handle with operator""s hands and by shifting the operating handle upward or downward.
FIG. 14 hereof shows such an operating handle of a prior art snow removing machine with a snow removing plate. The known snow removing machine 200 with the snow removing plate includes left and right operating handles 201, 201, which are spaced from one another. The left and right operating hands 201, 201 have respective left and right grip portions 202, 204. A clutch lever 203 is located in the vicinity of the left grip portion 202. An operation box 205 is mounted between the left and right handles 201, 201. The operation box 205 includes a shift lever 207 for changing over a forward and aft drive as well as a vehicle speed, and a governor control lever 208 located in the vicinity of the shift lever 207 for adjusting an engine speed.
During snow removing work using the snow removing machine having the snow removing plate, the engine is first operated and, then, the respective left and right grip portions 202, 204 are gripped with the operator""s left and right hands to thereby operate the snow removing plate via the operating handle 201.
During the snow removing work, the changeover between the forward and aft drive and the control of the vehicle speed are carried out by manipulating the clutch lever 203 with his left hand gripping the left grip portion 202 and, under such a condition, by manipulating the shift lever 207 with his right hand released from the right grip portion 204.
Further, upon adjustment of the engine speed, the governor control lever 208 is manipulated with the right hand released from the right grip portion 204.
When manipulating the clutch lever 207 and the governor control lever 208 with the right hand released from the right grip portion 204 during the snow removing work, it is required for the operator to manipulate the operating handle 201 by a single hand operation gripping only the left grip portion 202. This results in an increased load for the operator""s hands or arms.
When manipulating the operating hand 201 in the single hand operation, the operator encounters difficulty in determining the traveling direction of the snow removing machine 200. Especially in cases where there exists relatively large irregular road surfaces or in cases where snow contains a large amount of water, the snow removing plate is exerted with an increased load, thereby making the manipulation difficult to achieve with a single hand. Thus, the snow removing work should be inevitably interrupted once, thereby disturbing the improvement in the snow removing work efficiency.
A snow removing machine, which includes a rotary snow removing unit mounted to a front part of its body and crawls over snow through crawler belts to remove the snow, is disclosed, for example, in Japanese Utility Model Publication No. SHO-61-23059. The snow removing machine includes a height adjustment mechanism having indispensable components such as a cylinder, a piston and a piston rod for adjusting the height of the rotary snow removing unit, and an operation lever located in the vicinity of the grip portion for manipulating the height adjustment mechanism. The snow removing machine is arranged so as to adjust the height of the rotary snow removing unit by maintaining the height adjustment mechanism in a free condition under a gripped state of the operation lever and by moving the grip portion upward or downward. In such a snow removing machine, adjusting the height of the rotary snow removing unit enables the rotary snow removing unit to perform the snow removing work in dependence on irregular profiles or undulations of the snow surface.
However, in order to adjust the height of the rotary snow removing unit so as to meet the irregular profiles or the undulations, which consecutively extend, of the snow surface, the operator needs to implement two different operations involving one step of gripping the operation lever and the other step of moving the grip portion upward or downward, with a relatively increased load to be exerted to the operator. In addition, the upward or downward movement of the grip portion while gripping the operation lever causes difficulty to the operator in concentrating the upward or downward movement of the grip portion, thereby disturbing the improvement in the snow removing work efficiency.
It is therefore an object of the present invention to provide a snow removing machine which effectively reduces a load on an operator""s snow removing work to provide improved snow removing work efficiency.
According to an aspect of the present invention, there is provided a snow removing machine which comprises a vehicle body having a body frame, a snow removing section mounted to a front portion of the body frame for removing snow, an operating handle mounted to a rear portion of the body frame for performing operation, left and right grip portions mounted to the operating handle to be gripped by an operator, a forward and aft drive changeover switch mounted on one of the left and right grip portions for changing over a traveling direction of the vehicle body, a height control operation lever for adjusting a height of the snow removing section and a speed control operation lever mounted to the other one of the left and right grip portions for adjusting a traveling speed of the vehicle body.
In the thus-arranged snow removing machine, the forward and aft drive changeover switch and the height control operation lever, which adjusts the height of the snow removing section, are mounted on one of the grip portions, and the speed control operation lever is mounted on the other one of the grip portions. Under a circumstance wherein the respective grip portions are kept in a grip condition being gripped with operator""s both hands, as the operator uses his one hand to manipulate the forward and aft drive switch and the height control operation lever, it is possible for his other hand to manipulate the speed control operation lever. Consequently, the operator is enabled to use his both hands to operate the operating handle without carrying out a single hand operation.
Desirably, the snow removing machine further comprises a traveling frame for supporting drive wheels and idling wheels, between which crawler belts are stretched, by means of vehicular shafts, a height adjustment mechanism mounted between the traveling frame and the vehicle body to allow the height of the snow removing section to be adjusted when the height control operation lever is gripped to be brought into a free condition to enable tilting of the vehicle body and is subsequently released to be brought into a lock position, and a lever lock mechanism mounted to the operating handle having the one of the grip portion for allowing the height control operation lever to be locked for preventing the height control operation lever from returning from a position in a gripped state of the height control operation lever.
Thus, the presence of the lever lock mechanism mounted to the operating handle and enabled to allow the height control operation lever to be locked with the lever lock mechanism in a position gripped by the operator does not need to perform two different operations at the same time for raising or lowering the operating handle while manipulating the operation lever during adjustment of the snow removing section. As a consequence, it might be enough for the operator to merely operate the upward or downward operation of the operating handle.
In a preferred example arrangement, the lever lock mechanism comprises a lever segment mounted to the operating handle for swinging movement and having a lock recess, a spring member for retaining the lever segment in a lock position or a releasing position, and a lock pin located on the operation lever and capable of entering and engaging with the lock recess in a state wherein the lever segment is retained in the releasing position. With such a lever lock mechanism, the mere swinging movement of the lever segment of the lever lock mechanism allows the lock recess and the lock pin to engage with each other. Accordingly, the simple operation for the mere swinging movement of the lever segment renders the height control operation lever to be locked in a position gripped by the operator. The lever lock mechanism is constructed of three components of the lever segment, the spring member and the lock pin, with a resultant compact structure in the lever lock mechanism with a lowered cost.
In a second preferred example arrangement, the lever lock mechanism comprises a lever segment mounted to the operating handle for swinging movement, a spring member for retaining the lever segment in a releasing position, and a lock pin protruding from the lever segment and capable of engaging with the lock recess formed in the height control operation lever when the lever segment swings in a direction toward the lock position. With such a lever lock mechanism, the mere swinging movement of the lever segment of the lever lock mechanism allows the lock recess and the lock pin to engage with each other in the same manner as the first preferred example. Accordingly, the simple operation for the mere swinging movement of the lever segment renders the height control operation lever to be locked in a position gripped by the operator. The lever lock mechanism is constructed of three components of the lever segment, the spring member and the lock pin, with a resultant compact structure in the lever lock mechanism with a lowered cost.
In a preferred form, the height adjustment mechanism comprises a cylinder connected to one of the vehicle body and the traveling frame, a piston rod connected to the other one of the vehicle body and the traveling frame, a piston interconnected to the piston rod and received in the cylinder, a control valve located in the piston, and a force transmission member for transmitting a force, which opens the control valve, to the control valve in response to gripping motion of the operation lever, wherein high pressure gas is filled in the cylinder at both sides thereof. With such a height adjustment mechanism, the presence of the high pressure gas filled in the cylinder allows the control valve, when it is opened, to smoothly pass the high pressure gas. Comparing a case wherein oil is filled in the cylinder, the piston is enabled to move in a more smooth manner. This allows the operating handle to move upward or downward in a simpler manner, with a resultant further decrease in a load for the operator. Further, the presence of the high pressure gas filled in the cylinder allows impacts or vibrations, caused by the road surfaces or the snow surfaces, to be effectively absorbed with a compressive action of the high pressure gas when the control valve is closed.